Various types of cycloaddition such as [2+1], [2+3], and Diels-Alder reactions have been investigated for the purpose of exohedral functionalization of [60]fullerene and also in few cases of [70]fullerene. Thermal and photochemical activation have been used and lead to a variety of new fullerene derivatives which may be further functionalizable. In addition, a new approach to aza-heterofullerenes has been developed starting from an exohedrally activated fullerene.